The present invention relates to a jacketed tracer projectile with a metal core intended for small-caliber and medium-caliber weapons, comprising a tracer device disposed in the rear part of the projectile. The invention also relates to a method for the application of the tracer device in the projectile.
Jacketed tracer projectiles with a metal core intended for small-caliber ammunition in calibers up to and including 12.7×99 mm for rifles and submachine guns comprise a tracer charge normally disposed in the rear part of the projectile. The tracer charge is usually applied directly into a cavity intended for the purpose in the rear part of the projectile. Alternatively, the tracer charge is pre-installed in a so-called charge capsule, which is itself installed in the cavity by a shrinking or pressing process. A sealing wad/sealing disk is usually also disposed directly in connection with the tracer charge, the function of the sealing disk being to protect the jacket of the projectile from hot combustion gases, which are generated in conjunction with the combustion of the luminous charge. A sealing lacquer, which covers the open part of the tracer charge, is also included in certain cases, when moisture-sensitive pyrotechnic tracer charges are used, in order to protect against ambient moisture; see, for example, DE10022004 A1.
One problem associated with the aforementioned tracer projectiles concerns the attachment of the tracer charge in the projectile. Forces which act on the projectile during the discharge phase present the risk of the tracer charge becoming, separated, in whole or in part, from the projectile during the discharge phase. Examples of such influencing forces are the high pressures and temperatures acting on the projectile from behind caused by hot combustion gases from the tracer charge, uneven loading on the projectile caused by uneven combustion in the tracer charge in the radial direction, high compression pressures acting on the core of the projectile caused by high frictional forces between the rifling ribs of the barrel and the jacket of the projectile, and also high rotational forces on the projectile caused by the rifling ribs of the barrel during the acceleration phase of the projectile. Strong rotation of the projectile and the inertia of the tracer charge can lead to all or parts of the tracer charge becoming separated in the event of poor attachment of the tracer charge. Vibrations in the barrel of the weapon, so-called barrel-jump, can likewise lead to separations of the tracer charge. Barrel-jump is caused by vibrations in the barrel in the axial direction and/or in the radial direction, which vibrations are attributable to factors such as the rate of fire, the length of the barrel, the center of gravity and the strength.
A further problem associated with the aforementioned tracer projectiles is the number of parts that are used for the attachment of the luminous charge and for the protection of the jacket against combustion gases and against other external influences, such as moisture, which makes the tracer projectile complicated and expensive.
It is desirable to provide a tracer projectile intended for small-caliber and medium-caliber weapons comprising a tracer device, in particular a pyrotechnic tracer charge designed to reduce the risk of the tracer device, in whole or in part, becoming separated from its attachment in the projectile.
It is also desirable to provide a tracer projectile having few or no extra components for the attachment of the tracer device and for the protection of the jacket of the projectile.
Accordingly, what has been accomplished according to an aspect of the present invention is a jacketed tracer projectile with a metal core intended for small-caliber and medium-caliber weapons, comprising a tracer device disposed inside a cavity having a cross section S1,2 in the metal core in the rear part of the projectile, the cavity being designed for strong adhesion between the tracer device and the cavity.
The tracer projectile is characterized in that the cross section S1,2 of the cavity is polygon-shaped for strong adhesion to the interior walls of the cavity.
Further aspects of the tracer projectile according to preferred embodiments of the invention are indicated below:
According to one embodiment of the tracer projectile, the cross-sectional area S1 of the cavity is hexagon-shaped.
According to one embodiment of the tracer projectile, the cross-sectional area S2 of the cavity is star-shaped.
According to one embodiment of the tracer projectile, the tracer device is a pyrotechnic tracer charge.
According to one embodiment of the tracer projectile, the inner surface of the cavity has a surface roughness (Ra) in the range 0.2-3.2.
According to one embodiment of the tracer projectile, the cavity is cone-shaped in the axial direction, in the projectile, with a cone angle α in the range 0.2°-1.0°.
According to one embodiment of the tracer projectile, the metal core consists of steel.
Also accomplished according to an aspect of the present invention is a method for the application of a tracer device in a jacketed tracer projectile comprising a metal core.
The method is characterized by the following three steps:
1/ Machining of a cavity with a polygonal cross section S1 in the metal core,
2/ Machining of the interior walls of the cavity to a predetermined surface roughness (Ra) in the range 0.2-3.2, e.g. 0.5-1.5.
3/ Application of the tracer device in the cavity by a pressing process.
Further preferred embodiments of the method according to the invention are indicated below:
According to one embodiment of the method, the machining of the polygon-shaped cavity is performed in the metal core by a hot-forming method.
The invention, according to aspects thereof, entails a number of benefits and effects, of which the most important are:
The design of the cavity prevents the tracer device from becoming separated, in whole or in part, from its attachment as the projectile rotates strongly during the discharge phase.
The design of the cavity means that no extra components are required for the secure attachment of the tracer device.
The design of the cavity permits a simple and reliable manufacturing process of the projectile at low cost.